1. Field of the Invention
The present invention relates to a novel and useful process for producing polymers of .alpha.,.beta.-unsaturated carboxylic acid esters.
In particular the present invention relates to a new process for producing polymers of .alpha.,.beta.-unsaturated carboxylic acid esters containing a tertiary amino group, which comprises polymerizing an .alpha.,.beta.-unsaturated carboxylic acid ester containing a tertiary amino group in the presence of a specific phosphorus compound, and also relates to a novel process for producing polymers of .alpha.,.beta.-unsaturated carboxylic acid esters suitable for the production of block copolymers, which comprises polymerizing an .alpha.,.beta.-unsaturated carboxylic acid ester in the presence of an aforementioned polymer of an .alpha.,.beta.-unsaturated carboxylic acid ester containing a tertiary amino group. The thus obtained polymers of .alpha.,.beta.-unsaturated carboxylic acid esters containing a tertiary amino group and polymers of .alpha.,.beta.-unsaturated carboxylic acid esters can be effectively used in a wide variety of applications including paints, adhesives, moldings, fibers and fiber processing.
2. Background Art
Currently, polymers of .alpha.,.beta.-unsaturated carboxylic acid esters are typically produced by a radical polymerization method, and this method has been used for the production of various kind of such polymers. However, the production of polymers of high molecular weight by radical polymerization has required the application of bulk polymerization methods or suspension polymerization methods in which the control of heat generation is extremely problematic. Moreover, radical polymerization is unsuitable for the production of block copolymers.
Furthermore, anionic polymerization methods have also been widely investigated as a method for synthesizing polymers of .alpha.,.beta.-unsaturated carboxylic acid esters. The synthesis of block copolymers is possible using anionic polymerization methods, but because the polymerization must be conducted at low temperatures and under anhydrous conditions, it cannot be regarded as a generally applicable synthetic method.
Moreover, recently reported methods for synthesizing block copolymers include a method using a ketene silyl acetal as an initiator [D. Y. Sogah et. al., Macromolecules, 20, p.1473-1488 (1987)], a method using a metal porphyrin complex as an initiator [Kuroki et. al., Polymer Preprint, Japan, 37(6), p.1327-1329 (1988)], and a method using a lanthanoid complex as an initiator. However, in all of these methods not only is the synthesis of the initiator extremely complicated, but there are several additional drawbacks, including a lack of stability of the initiators making the general usage thereof difficult, the requirement that the polymerization be carried out under anhydrous conditions, the inability to polymerize monomers containing active hydrogen, and remarkable discoloration of obtained polymers due to the contamination of metals originating from the initiator.